RESUMO
The stargazer (stg) mouse exhibits severe cerebellar ataxia, abnormal motor behavior, and absence epilepsy. Selective failure of cerebellar brain-derived neurotrophic factor (BDNF) expression is one of the molecular defects in stg mutant. To determine the in vivo effect of BDNF replacement on cerebellar function, we generated a double mutant line of stg-BDNF mice by crossbreeding BDNF-overexpressing transgenics with stg mutants. Significant upregulation of BDNF mRNA and protein levels was confirmed in the double mutant cerebellum. Gross examination showed less severe ataxia with normal cerebellar cytoarchitecture in stg-BDNF mice than the original stg mice. Behavioral characterization of stg-BDNF mice revealed significantly improved performance in swimming test and footprint analysis compared to stg mice. These results provide in vivo evidence for the correlation of the cerebellar BDNF levels to the ataxia and motor behaviors of stg mice.
Assuntos
Ataxia/fisiopatologia , Ataxia/terapia , Fator Neurotrófico Derivado do Encéfalo/fisiologia , Canais de Cálcio/genética , Atividade Motora/genética , Análise de Variância , Animais , Ataxia/genética , Autorradiografia , Comportamento Animal , Fator Neurotrófico Derivado do Encéfalo/genética , Cerebelo/diagnóstico por imagem , Cerebelo/metabolismo , Regulação da Expressão Gênica/genética , Hibridização In Situ , Camundongos , Camundongos Transgênicos , Desempenho Psicomotor/fisiologia , RNA Mensageiro/metabolismo , Radiografia , Tempo de Reação/genética , Natação/fisiologiaRESUMO
Tamoxifen is an anticancer drug that induces oxidative stress and apoptosis via mitochondria-dependent and nitric oxide (NO)-dependent pathways. The present report shows that tamoxifen increases intramitochondrial ionized Ca(2+) concentration and stimulates mitochondrial NO synthase (mtNOS) activity in the mitochondria from rat liver and human breast cancer MCF-7 cells. By stimulating mtNOS, tamoxifen hampers mitochondrial respiration, releases cytochrome c, elevates mitochondrial lipid peroxidation, increases protein tyrosine nitration of certain mitochondrial proteins, decreases the catalytic activity of succinyl-CoA:3-oxoacid CoA-transferase, and induces aggregation of mitochondria. The present report suggests a critical role for mtNOS in apoptosis induced by tamoxifen.
Assuntos
Apoptose/efeitos dos fármacos , Neoplasias da Mama/tratamento farmacológico , Mitocôndrias/efeitos dos fármacos , Óxido Nítrico Sintase/metabolismo , Tamoxifeno/farmacologia , Animais , Antineoplásicos Hormonais/farmacologia , Neoplasias da Mama/enzimologia , Cálcio/metabolismo , Linhagem Celular Tumoral , Citocromos c/metabolismo , Feminino , Humanos , Peroxidação de Lipídeos , Mitocôndrias/enzimologia , Mitocôndrias Hepáticas/efeitos dos fármacos , Mitocôndrias Hepáticas/enzimologia , Estresse Oxidativo/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Ácido Peroxinitroso/biossíntese , Ratos , Ratos Sprague-DawleyRESUMO
The present study demonstrates that mitochondrial cytochrome c reacts with the thiol-reacting agent N-ethylmaleimide (NEM) to produce a one NEM-adducted cytochrome c. Mitochondrial cytochrome c also reacts with 5,5'-dithio-bis-(2-nitrobenzoic acid) and 1-chloro-2,4-dinitrobenzene in a manner prevented with NEM or iodoacetic acid (IAA). NEM-treated cytochrome c has lower reducibility and lower function to support mitochondrial oxygen consumption. These findings suggest that mitochondrial cytochrome c contains a reactive thiol that is involved in the functions of cytochrome c for mitochondria. Nitric oxide reacts with the cytochrome c thiol to generate S-nitroso (SNO)-cytochrome c in a manner prevented with NEM or IAA. SNO-cytochrome c has lower reducibility and function to support mitochondrial oxygen consumption, similar to NEM-treated cytochrome c.